The long term goal of the proposed research is to increase the understanding of the anatomical basis of visual information processing in the geniculostriate system of normal and visually deprived primates. The focus will be on rhesus monkeys during their first few weeks of life. The first goal is to study in the lateral geniculate nucleus (LGN) and area 17 the normal maturational sequence of certain putative neuromodulator/neurotransmitter systems to determine whether these substances have the potential to play a functional role during the system's normal development. Another focus will be on layer 4 of area 17.
One aim i s to study exact time course and progress of segregation of left and right eye inputs into ocular dominance columns (ODC) to establish for how long and to what degree the initial overlap of these inputs persists in early life. Another aim is the determination of the time course of maturation of the different horizontal subdivisions of this layer which receive magno- or parvocellular LGN input, and thus to determine whether these 2 channels follow different maturation times. The baseline data will serve to evaluate consequences of early postnatal interventions into the development of the geniculostriate system via different types of visual deprivation to study the effects of the selective deprivation paradigms on the interactions between LGN and area 17. Identification of other anatomical consequences of deprivation, i.e. changes in enzyme and transmitter distribution, is equally important. Cyto- and immunohistochemical methods, and orthograde and transneuronal transport techniques will be used. Birth is the time when visual experience exerts its first impact on the system, and is capable of initiating events which can determine the future course of the proper functional development of the system. Therefore, these studies should help to determine how neuronal development proceeds under normal visual stimulation and to which degree abnormal stimulation effects this development in early infancy. These studies may uncover some basic mechanisms underlying not only normal visual information processing, but also visual system dysfunctions. Because of close similarities between the rhesus monkey's and the human visual system, the data are highly relevant for the clinical management of human visual system disorders like amblyopia, strabismus and congenital cataracts.
